deps-upgrade— agent skill

Dependencies are inherited code. Upgrades are inherited risk. Patch in batch, minor in batch with a smoke test, major one-at-a-time with a CHANGELOG read.

When to Apply / NOT

Apply: CVE remediation; major upstream release; compatibility forcing function; quarterly hygiene cadence; pre-release lockfile audit; deprecation warnings accumulating.

NOT apply: active feature branch with high churn; pre-release freeze window; mid-incident; API-break-driven refactor.

Anti-patterns

• Big-bang upgrade: bumping every dep at once.
• Skipping the lockfile: floating ranges create non-reproducible builds.
• Ignoring the CHANGELOG: major bumps without reading upstream notes.
• Suppressing deprecations: --warning-as-error=off defers cost.
• Bypassing audit signals: npm audit fix --force without reading.
• No smoke test on minor: minor versions can introduce behavior shifts.
• Forgetting transitives: surface deps look fine; transitive CVE remains.
• Mixing concerns in one commit: upgrade + refactor + feature — atomize per <git> policy.

Workflow (language-neutral)

1. Inventory — enumerate manifests + lockfiles across ecosystems. Many canonical names are extensionless (go.mod, Gemfile, pom.xml); filtering by extension alone misses them. fd only takes one glob per call, so anchor on canonical filenames via a single regex:

   fd -t f '^(package(-lock)?\.json|pnpm-lock\.yaml|yarn\.lock|Cargo\.(toml|lock)|pyproject\.toml|poetry\.lock|requirements.*\.txt|Pipfile\.lock|go\.(mod|sum)|pom\.xml|build\.gradle(\.kts)?|settings\.gradle(\.kts)?|libs\.versions\.toml|gradle\.lockfile|Gemfile(\.lock)?|.*\.gemspec|.*\.opam|dune-project|opam\.locked|mix\.(exs|lock)|composer\.(json|lock))$'

Add ecosystem-specific names if the project uses something rarer (Pipfile, Brewfile, flake.nix, shard.yml, pubspec.yaml). Capture a lockfile snapshot for later diff (difft).

1. Scan outdated — run ecosystem outdated/upgradable command. Capture report.
2. Categorize — bin every candidate as patch / minor / major.
3. Patch batch — bump all patches at once; lockfile-only diff. Run full test suite. Commit chore(deps): patch sweep.
4. Minor batch — bump minors together; smoke-test. Read each minor CHANGELOG. Commit chore(deps): minor sweep.
5. Major individually — one major version per commit. Read CHANGELOG / migration guide first; apply codemod or manual edits; run full suite + adversarial tests. Commit chore(deps)!: bump <pkg> <old>→<new>.
6. Lockfile audit — compare pre/post with difft (not diff). Check transitive churn.
7. Re-scan — run CVE scanner again post-upgrade.
8. Hand off — major upgrade requires API-break propagation → cross to a refactor / break-compat workflow. New CVEs → hand to security-audit workflow.

Breaking-Change Review Checklist

For each major bump, before writing any code:

• Read upstream CHANGELOG.md / MIGRATION.md / release notes
• Identify removed/renamed/behavior-changed/default-changed APIs
• Check for codemod / mod-tool the upstream supplies
• Run tests with deprecation-warnings-as-errors enabled
• Search for direct usage with git grep -n -F '<symbol>' and ast-grep -p '<pattern>'
• Verify peer-dep / runtime-version compatibility matrix
• Verify license has not changed in a blocking direction
• Verify SBOM diff matches expected dependency-tree change

Parallel Lockfile / Upgrade Tooling

Use fd -e <ext> (not find). Use difft (not diff). Use bat -P -p -n (not cat). Use git grep -n -F (not grep).

Constitutional Rules

1. Lockfile is law — always commit lockfile diffs.
2. Atomic commits — one bin per commit; one major per commit.
3. Read the CHANGELOG — major bump without primary-source review forbidden.
4. Test after every bin.
5. Re-scan post-upgrade.
6. Deprecations are debt — file follow-ups.
7. Do not bypass audit signals.

Tooling notes

• difft is the mandated lockfile diff viewer; diff is banned.
• hyperfine validates upgrade did not regress hot-path performance.